def fz(n):
    ct=1
    f=1
    while f<=n:
        ct*=f
        f+=1
    return ct
def fm(n):
    ct=0
    f=1
    while f<=n:
        ct+=f
        f+=1
    return ct
def sum(n):
     s=0
     t=1
     while t<=n:
         s=s+fm(t)/fz(t)
         t+=1
     return s

n=int(input())
s=sum(n)
print(s)

